1. Field Of The Invention
The system of the present invention relates to the monitoring and control of hydrogen sulfide gas in a waste water stream. More particularly, the present invention relates to a system for continuously monitoring the hydrogen sulfide concentration present in a waste water stream and controlling the quantity and time of automatically injecting a specified chemical into the waste water stream.
2. General Background
In the environmental waste water industry, it is critical that hydrogen sulfide gas, which is a toxic gas in certain concentrations, be monitored and controlled. For example, in a waste water stream such as a sewerage system of a municipality, depending upon the concentration of hydrogen sulfide in the waste water stream, some of it may evaporate into the air in its toxic gaseous form. It is therefore critical that the amount of gas in the atmosphere above the stream be closely monitored and controlled so that people do not come into contact with the deadly gas when working within the confines of the system.
In the present state of the art there are systems for monitoring the quantity of hydrogen sulfide gas in the air above a sewerage stream. However, these present state of the art methods require manual monitoring of the stream during specific time intervals and manual testing of the air through a standard testing procedure. This falls very far short of a system that continuously monitors the air above the waste water stream and controls the level of hydrogen sulfide through chemical injection.
There are several patents in the art which either address the system of monitoring hydrogen sulfide gas, or the chemical compounds which are added to the waste water stream in order to control the amount of hydrogen sulfide gas, the most pertinent patents being as follows:
______________________________________ PATENT NO. TITLE ISSUE DATE ______________________________________ 4,978,512 COMPOSITION AND 12/18/90 METHOD FOR SWEETENING HYDROCARBONS 4,891,205 STABILIZED CHELATING 01/02/90 AGENTS FOR REMOVING HYDROGEN SULFIDE 4,778,609 HYDROGEN SULFIDE 10/18/88 SUPPRESSION WITH AMINE DERIVATIVE 4,748,011 METHOD AND 05/31/88 APPARATUS FOR SWEETENING NATURAL GAS 4,680,127 METHOD OF 07/14/87 SCAVENGING HYDROGEN SULFIDE 4,515,759 PROCESS OF 05/07/85 REMOVING HYDROGEN SULFIDE FROM GAS MIXTURES 4,443,423 METHOD OF 04/17/84 REMOVING HYDROGEN SULFIDE FROM GASES UTILIZING A POLYVALENT METAL CHELATE 4,436,713 METHOD OF 03/13/84 REMOVING HYDROGEN SULFIDE FROM GASES UTILIZING A POLYVALENT METAL 4,405,581 PROCESS FOR THE 09/20/83 SELECTIVE REMOVAL OF HYDROGEN SULFIDE FROM GASEOUS MIXTURES WITH SEVERELY STERICALLY HINDERED SECONDARY AMINO COMPOUNDS 4,380,586 METHOD AND 04/19/83 APPARATUS FOR PHOTOMETRICALLLY MONITORING LOW LEVEL CONCENTRATION OF HYDROGEN SULFIDE IN ALKANOL AMINE 4,112,049 ABSORPTION OF SULFUR 09/5/78 COMPOUNDS FROM GAS STREAMS 4,107,270 PROCESS FOR 08/15/78 SIMULTANEOUS REMOVAL OF HYDROGEN SULFIDE AND WATER FROM A GAS MIXTURE WITHOUT 2,860,030 RECOVERY OF 11/11/58 HYDROGEN SULFIDE AND/OR CARBON DIOXIDE SUBSTANTIALLY FREE FROM HYDROCARBONS AND 2,761,818 RECOVERY OF 09/04/56 ETHANOLAMINES ______________________________________